Vice President Teofisto Guingona threatened to resign yesterday, saying he was bypassed by the military and the police who went straight to President Gloria Arroyo for approval of controversial United States-Philippine war games in Zamboanga City and Basilan, even as U.S. soldiers set up camp yesterday on an island in the southern Philippines where they will join operations against a militant group linked to Osama bin Laden.

"I was suddenly out during deliberations. I am still waiting for the documents. I think they were given to other divisions in the foreign affairs office," Guingona who is also foreign secretary reportedly said, as rumours swirled in the capital that he was initially kept in the dark about the U.S. deployment.

Guingona later denied rumours he had resigned as foreign secretary because of differences with President Arroyo over the issue. "I am still the foreign secretary," he told reporters after a meeting with Arroyo.

Several pro-administration senators recently asked Guingona to explain why he allowed the entry of American soldiers and consultants near the war zone between Philippine government soldiers and the hostage-taking Abu Sayyaf in Basilan. The militants still hold two American missionaries and one Filipina nurse in hideouts in Basilan.

Meanwhile, Presidential Spokesman Rigoberto Tiglao denied Guingona's claim, saying the vice president had attended several deliberations on the matter, with Defence Secretary Angelo Reyes and Armed Forces Chief of Staff Diomedio Villanueva.

Guingona was in the final meeting to discuss the U.S.-Philippine plan when Arroyo had asked for a consensus before giving her final go-ahead to the holding of war games in Zamboanga City and Basilan.

Arroyo said the joint exercises are not against the Constitution and that she cannot be impeached for allowing it.

"It's not a violation of the Constitution because they are not here to do combat. They are here to do training, so that's not a violation. We do the Balikatan (joint exercises) every year. There is no resumption of U.S. bases in the country. Can anyone point out where the U.S. bases are? A base arrangement is a very technical arrangement and no way is their (U.S. soldiers) visit here anywhere near the meaning of a base," she added.

"The American soldiers won't be on the front line. They will be behind our own soldiers, observing their operations," said Arroyo. The American soldiers were authorised to shoot back in self-defence if attacked by the Abu Sayyaf. Participants will be using live bullets in the war games.

About 160 American soldiers arrived in Zamboanga City and Basilan this month. A total of 1,600 American soldiers will be based in Zamboanga in February. The average arrival is about 4,000 in six months.

Tiglao denied the joint military training are operations against the Abu Sayyaf, adding the presence of 160 American soldiers with 6,000 Philippine military troops in Mindanao does not constitute a military operation against known local terrorists.

Philippine defence officials said the exercise would also lead to the rescue of the American hostages and the Filipina nurse.

The U.S. special forces will train Filipino troops, provide tactical advice, but above all extend intelligence, surveillance and reconnaissance assets to track Abu Sayyaf rebels in Basilan, said a Pentagon official in a wire story that reached Manila.

"It's not just training on its own. It's assistance. We can advise, train and assist," said the same official, who insisted that the U.S. troops would not participate actively in Filipino operations.

"Certainly, when there's a situation where American hostages are being held, that adds a dimension to our interest," the U.S. Defence Secretary Donald Rumsfeld was quoted as saying in a Pentagon news conference.

Air Force Brig. Gen. Donald Wurster, commander of the U.S. Special Operations in the Pacific, was identified as head of the U.S. forces, but Philippine authorities said all the American soldiers would be under a Philippine commanding officer.

The war games are part of the implementation of the Philippine-U.S. Visiting Forces Agreement, which was ratified by the Senate in 1998. They were always held in several camps outside of the war zone between government troopers and known hot beds of insurgents in the country.

Opposition senators hinted at impeachment proceedings against Arroyo, saying she has allowed an unconstitutional precedent.

But several sections of the society have defended Arroyo.

"We are happy they are here. We are lucky to have been chosen as the site for the exercises," said Zamboanga City Mayor Maria Clara Lobregat, adding the Philippine military is "the least trained in this part of the world".

"It's about time (the Philippine Armed Forces) are trained in using modern weapons. We have a chance now for the Americans to help us train our people, bring in weapons and all that."

"I don't think we should be very concerned with sovereignty issues especially in this day and age when the community of nations are solidly acting together to combat any form of global terrorism," said Undersecretary Manuel Teehankee.

The 1987 constitution bars foreign bases, troops or facilities on Philippine soil unless covered by a treaty. The two countries are bound by a Mutual Defence Treaty.